Production Method for Pulp Foam Cushioning Material, Shaping Mold for the Same, and Pulp Foam Cushioning Material

This application claims priority to Japanese Patent Application No. 2024-076224 filed on May 9, 2024, which is incorporated herein by reference in its entirety including the specification, claims, drawings, and abstract.

The present specification discloses a method for producing a pulp foam cushioning material used as a buffer material, a shaping mold for molding a pulp foam cushioning material, and a pulp foam cushioning material.

Buffer materials, being molded pulp foam cushioning materials, are disclosed, for example, in JP 3017716 B, JP 3038158 B, JP 3125351 B, JP 3240664 B, JP 3240676 B, and JP 3278922. In a process of producing a pulp foam cushioning material, for example, a pulp feedstock composed of shredded pieces of pulp is mixed and kneaded with water and a foaming material by means of a mixer or the like. A foamy substance obtained by kneading is filled into a mold. As the mold, a metallic mold is used, for example. The foamy substance filled into the mold is dehydrated to obtain a porous pulp foam cushioning material.

In this regard, when there are variations in dehydrated conditions among regions of a foamy substance, the foamy substance may exhibit a nonuniform distribution of porosities. With this in view, the present specification discloses a production method of a pulp foam cushioning material in which nonuniformly dehydrated regions are reduced from those in related art, and discloses a shaping mold for a pulp foam cushioning material, and the pulp foam cushioning material molded using the shaping mold.

The present specification discloses a production method for a pulp foam cushioning material. The production method includes the steps of mixing and kneading a pulp feedstock, composed of shredded pieces of a pulp raw material, with water and a foaming agent to obtain a foamy substance, filling a shaping mold with an amount of the foamy substance that is greater than a volume of a pulp foam cushioning material, compressing the filled foamy substance, and dehydrating and drying the foamy substance. The shaping mold includes a mold main body which is entirely composed of a breathable material. In the drying step, the foamy substance is dehydrated and dried in a state where the mold main body surrounds all surfaces of the foamy substance.

According to the above-described configuration, the mold main body is, in its entirety, composed of the material having an air permeable property. Therefore, the foamy substance can be dehydrated through the entire surface of the mold main body. Further, according to the above-described configuration, the foamy substance is filled into the shaping mold to the amount greater than the volume of the pulp foam cushioning material, and compressed in the shaping mold. This allows the foamy substance to be in contact with the mold main body composed of the breathable material throughout the entire inner surface of the mold main body.

In the above-described configuration, a step of inserting a mesh panel between the shaping mold and the foamy substance may be included between the filling step and the compressing step.

According to the above-described configuration, a mesh pattern of the mesh panel can be transferred to a surface of the pulp foam cushioning material. In other words, the surface of the pulp foam cushioning material can be formed as a design surface.

The present specification further discloses a shaping mold for a pulp foam cushioning material. The shaping mold is filled with a foamy substance. The foamy substance is produced by mixing and kneading a pulp feedstock, composed of shredded pieces of a pulp raw material, with water and a foaming agent. The shaping mold for a pulp foam cushioning material includes a mold main body. The mold main body is entirely composed of a breathable material.

According to the above-described configuration, the mold main body is entirely composed of the breathable material. Therefore, the foamy material can be dehydrated through the entire surface of the mold main body.

In the above-described configuration, the mold main body may be formed of flexible members. In this case, the shaping mold for the pulp foam cushioning material includes an external frame unit. The external frame unit supports the shape of the mold main body from its outside.

According to the above-described configuration, because the mold main body is formed of the flexible members, the flexible members will be deformed when an excessive pressure is applied to the foamy substance. In this way, flexibility of the pulp foam cushioning material can be ensured. In addition, because the external frame unit is provided, an easily deformable shape of the mold main body is supported from outside.

Further in the above-described configuration, the mold main body may be composed of a plurality of divided sub parts.

According to the above-described configuration, in contrast to the mold main body formed as one unit, releasability is improved.

In the above-described configuration, the plurality of sub parts may include a cross-shaped component and a columnar component. The cross-shaped component includes cross walls. The cross walls divide the pulp foam cushioning material into four portions. Further, a through hole is formed at the center of the cross walls. The columnar component is inserted into the through hole.

According to the above-described configuration, breathability of the mold main body is improved when the columnar component is removed from the through hole in a process of dehydrating the foamy substance.

Further, in the above-described configuration, the mold main body may include outer wall components, a first lid component, and a second lid component. The outer wall components surround the cross-shaped component. Further, the outer wall components are longer than the cross-shaped component. The first lid component is inserted into a filling space surrounded by the outer wall components, so as to be placed on the cross-shaped component. The second lid component is thicker than the first lid component and stacked on the first lid component. After the filling space is filled with the foamy substance, the foamy substance is downwardly pushed in by both the second lid component and the first lid component. Then, the second lid component is removed after the foamy body is pushed in.

According to the above-described configuration, because a thick lid consisting of the first lid component and the second lid component is used when the foamy substance is pushed in, the pressure applied to the foamy substance is rendered uniform. In addition, breathability in an upper portion of the mold main body can be ensured by removing the second lid component after the foamy substance is pushed in.

Still further, in the above-described configuration, the first lid component may have a water absorbing property superior to that of the cross-shaped component and the outer wall components.

According to the above-described configuration, the first lid component has a greater power of holding the foamy substance than that of the cross-shaped component and the outer wall components. Therefore, the first lid component can help the foamy substance to resist gravitational attraction, and thus can hinder the foamy substance from sagging. As a result, a surface conforming to the shape of the first lid component can be molded.

Further, in the above-described configuration, the shaping mold may be equipped with a filling mechanism disposed above the mold main body and the external frame unit. The filling mechanism includes a sleeve and a piston. The sleeve is configured to fill the foamy substance into the mold main body from thereabove. The piston is inserted into the sleeve. The sleeve is formed of a water impermeable material. In addition, the inner wall surface of the sleeve is a smooth surface.

When a portion of the foamy substance is spilled out of the mold main body, the spilled portion of the foamy substance will become fins or burrs after drying. According to the above-described configuration, however, because the inner wall surface of the sleeve is water impermeable and smooth, it is difficult for the foamy substance to remain within the sleeve. This can prevent the creation of fins or burrs.

In the above-described configuration, the shaping mold may include a mesh panel configured to be inserted between the cross-shaped component and the first lid component.

According to the above-described configuration, a mesh pattern of the mesh panel can be transferred to a surface of the pulp foam cushioning material. In order words, the surface of the pulp foam cushioning material can be formed as a design surface.

The present specification further discloses a pulp foam cushioning material. The cushioning material is produced by mixing and kneading a pulp feedstock, composed of shredded pieces of a pulp raw material, with water and a foaming agent to obtain a foamy substance, and drying the foamy substance. The pulp foam cushioning material includes a core layer being a foamed layer, and a skin layer covering all surfaces of the core layer. A density of fibers in the skin layer is higher than a density of fibers in the core layer.

According to the above-described configuration, all surfaces of the core layer having flexibility and a cushioning property are covered by the skin layer having the relatively higher density of fibers. As a result, decomposition or exfoliation of the core layer can be suppressed.

In the above-described configuration, the pulp foam cushioning material includes a bottom wall and a plurality of side walls. The plurality of side walls extend upward from the bottom wall and are separated from each other. The bottom wall and the plurality of side walls define a central hole. Each of the bottom wall and the side walls includes a core layer being the foamed layer and a skin layer covering the core layer. In addition, the core layer in each of the side walls has a cushioning property superior to that of the core layer in the bottom wall.

According to the above-described configuration, a commodity housed in the central hole is mainly retained by the side walls of the pulp foam cushioning material. In this way, the commodity having a side area greater than a bottom area is reliably retained by the pulp foam cushioning material.

In the above-described configuration, a density of fibers in the core layer of the bottom wall may be higher than a density of fibers in the core layer of the side wall.

According to the above-described configuration, the core layer of the bottom wall is hardly dented or depressed, and the commodity is prevented from sinking in the bottom wall. As a result, the commodity retained by the side walls is constrained so as not to move in a height direction of the side walls.

Further, in the above-described configuration, the side walls may be thicker than the bottom wall.

In this way, an allowance for crushing to a certain degree can be secured in the side walls.

The production method of a pulp foam cushioning material, the shaping mold for a pulp foam cushioning material, and the pulp foam cushioning material produced using the shaping mold disclosed herein can provide an effect that unevenly dehydrated regions in the foamy substance can be reduced compared to those in related art.

Hereinafter, a method for producing a pulp foam cushioning material, a shaping mold for a pulp foam cushioning material, and the pulp foam cushioning material molded using the shaping mold will be explained according to an embodiment with reference to the drawings. Shapes, materials, the number of items, and numerical values explained below are presented by way of illustration, and may be changed as appropriate depending on specifications of the shaping mold and the pulp foam cushioning material. It should be noted that identical or equivalent components are identified by identical reference numerals throughout the drawings.

A foamy substanceillustrated inis filled into a mold main bodyillustrated in. Then, as illustrated in, the filled foamy substanceis compressed by means of a first lid componentand a second lid component. Following this, as illustrated in, the mold main bodyis placed in a dryerin a state where the mold main bodyis housed in an external frame unit. The foamy substanceis dehydrated within the dryerto obtain a pulp foam cushioning materialas illustrated in.

Referring to, ingredients of the foamy substanceinclude water, a pulp feedstock, and a foaming agent. The pulp feedstockis obtained by shredding a pulp raw material, such as a corrugated cardboard, for example.

The foaming agentis, for example, a surfactant. The foaming agentmay be formed of an ordinary household material in order to reduce the load on the environment and impact on the human body. For example, the foaming agentmay be formed of any one of laundry detergent, body soap, or shampoo.

Firstly, the waterand the pulp feedstockare introduced into a mixer. For example, substantially equal volumes of the waterand the pulp feedstockare introduced into the mixer. Then, the mixeris closed by a lidand subsequently actuated. In this way, the pulp feedstockis kneaded with waterwhile being further shredded and pulverized. As a result, slurryis obtained.

Secondly, the foaming agentis added to the slurry. An amount of the foaming agentmay be approximately one-tenth of the amount of water, for example. After the addition of the foaming agent, the lidis closed to actuate the mixeragain. The slurryis kneaded with the foaming agent, and the foamy substanceis obtained. The foamy substanceis introduced into a shaping mold. The shaping mold includes the mold main bodyand the external frame unitshown in.

shows an exploded perspective view of the shaping mold according to the embodiment. The shaping mold includes the mold main bodyand the external frame unit. The mold main bodyis, in its entirety, formed of a breathable material. Further, the mold main bodyis composed of flexible members, for example. The mold main bodyis formed of sponge, for example. In other words, the mold main bodyis formed of a porous member in which spongin fibers constitute a netted structure.

The mold main bodyis composed of a plurality of divided sub parts. For example, the mold main bodyincludes a base, a cross-shaped component, a columnar component, outer wall componentsA,B,C andD, a first lid component, and a second lid component.

The baseis a rectangular plate member. As illustrated in, the cross-shaped componentis placed on the base. The cross-shaped componentincludes a square tubeand partition wallsA,B,C andD.

The square tubeis disposed at the center of the cross-shaped component. A through holeis formed through the square tube. Before the foamy substanceis introduced, as shown in, the columnar componentis inserted into the square tube. That is, the through holeis closed by the columnar component.

The partition wallsA,B,C, andD respectively extend forward, rearward, leftward, and rightward from the square tube. That is, the partition wallsA,B,C, andD constitute cross walls. Further, the through holeis formed at the center of the cross walls.

The partition wallsA andC are disposed on opposite sides of the square tube. In addition, the partition wallsB andD are disposed on opposite sides of the square tube. A distance Wfrom an extreme end (farthest from the square tube) of the partition wallA to an extreme end of the partition wallC is equal to a width Wof the base. In addition, a distance Lfrom an extreme end of the partition wallB to an extreme end of the partition wallD is equal to a length Lof the base.

The partition wallsA,B,C, andD correspond to slitsA,B,C, andD in the pulp foam cushioning material. In other words, the partition wallsA,B,C, andD divide the pulp foam cushioning materialinto four portions (side wallsA,B,C, andD).

To improve releasability, upper edges (ends farthest from the base) of the partition wallsA,B,C, andD are finished by R-processing. That is, the tops of the partition wallsA,B,C, andD are formed in a round shape.

The outer wall componentsA,B,C, andD have a shape of the L letter in a top view. The outer wall componentsA,B,C, andD are longer than the cross-shaped component. In other words, the height of the outer wall componentsA,B,C, andD is greater than the height of the cross-shaped component. For example, the height of the outer wall componentsA,B,C, andD is twice the height of the cross-shaped component.

The outer wall componentsA,B,C, andD include L-shaped wallsA,B,C, andD, respectively. RecessesA,B,C, andD are formed in lower regions on both ends (i.e., both wing tips) of the L-shaped wallsA,B,C, andD. As shown in, the recessesA andB engage an end region of the partition wallA. Similarly, the recessesB andC engage an end region of the partition wallB, and the recessesC andD engage an end region of the partition wallC. Further, the recessesA andD engage an end region of the partition wallD.

Referring to, an inner surface of the outer wall componentD may be marked by a guideline. The guidelineis a datum line indicating a level to which a lid membershould be pushed in. The distance from the guidelineto the top surface of the cross-shaped componentis greater than the sum of thicknesses of the first lid component, the second lid component, and the lid member. That is, as can be seen from the presence of a clearance Dshown in, when the lid memberis pushed to the level of the guideline, the bottom surface of the first lid componentis spaced from the top surface of the cross-shaped component. Such an empty space is filled with a portion of the foamy substance. The portion of the foamy substancefilled into the space constitutes a bottom wallof the pulp foam cushioning material.